Liquid crystal displays (LCDs) are advantageous in being light, thin and having low power consumption. They are being widely used in modern information devices such as notebook computers, mobile phones, and personal digital assistants (PDAs).
FIG. 1 shows an array substrate of a conventional liquid crystal display. The LCD array substrate 110 comprises a signal introducing region 111 and a display region 113. Data line pads 121 and scanning line pads 131 are formed in the signal introducing region 111. A plurality of data lines 122 and scanning lines 132 are respectively connected to the data line pads 121 and the scanning line pads 131. A plurality of pixels P is defined in a region where the data lines and the scanning lines cross. A data signal and a scanning signal are externally inputted via the data line pads 121 and the scanning line pads 131, and then transmitted to the respective pixels P in the display region 113 through the data lines 122 and the scanning lines 132. An adhesive sealing is provided outside the display region 113 for adhering the LCD array substrate and a color filter together.
In manufacturing processes for conventional LCD array substrates, defects such as a break and the like may occur in the data lines. As shown in FIG. 1, the data line 122 is broken at a point D1 in the display region 113. In this case, a data signal cannot be transmitted to the data line below the break D1, thereby causing a so-called line defect.
In order to repair the line defect in the array substrate, U.S. Pat. No. 6,111,558 discloses a repair structure. In the structure, as shown in FIG. 2 of the present application, a data line 122 comprises three portions, that is, a front data line portion 122a outside the display region and connected with a data line pad 121, a display region data line portion 122b, and an end data line portion 122c outside the display region and at the side away from the data line pad 121. In addition, a repair line 223 is provided outside the display region 113 of the array substrate 110. In the plan view of the array substrate of FIG. 2, the repair line 223 crosses with the front data line portion 122a and the end data line portion 122c perpendicularly. However, in a direction perpendicular to the surface of the array substrate, the repair line 223 and the data line 122 are positioned in different layers separated by an insulating layer therebetween. Hence the repair line 223 and the data line 122 are normally not in an electrical connection.
When a break point D2 occurs as shown in FIG. 2, the front data line portion 122a and the repair line 223 are electrically connected at the crossing point 2A, and the end data line portion 122c and the repair line 223 are electrically connected at the crossing point 2B by laser melting. Thus, a data signal on the data line can be transmitted to the repair line 223 via the crossing point 2A through the front data line portion 122a, and then via the point 2B to the data line below the break point D2. In this manner, the line defect is repaired.
FIG. 3 is a sectional view of the repairing structure along the I-I line of FIG. 2. Repair lines 223a and 223b are formed on a glass substrate 260 of an LCD array substrate 26 and in the same process as the scanning lines. Then a gate insulating film 261 and a passivation layer 262 are formed so as to overlay the repair lines 223a and 223b. A color filter 27 is provided at a position opposite to the LCD array substrate 26, and a light shield layer 271, an insulating layer 272 and a transparent common electrode 273 are formed on the color filter 27 from below to top. The LCD array substrate 26 and the color filter 27 are adhered together with an adhesive sealing 240, with liquid crystal 48 between the array substrate 26 and the color filter 27.
However, in the conventional techniques, all the repair lines are positioned in the same layer. In this case, when there are signals transmitting on two adjacent repair lines, for example repair lines 223a and 223b in FIG. 3, the two repair lines will interact with each other due to parasitic capacitance. In addition, the repair lines are typically made of the same material (Mo and AlNd for example) and in the same process with the scanning lines, leading to a significant resistance.